Cooling module for laser, fabricating method thereof, and semiconductor laser fabricated from the module

ABSTRACT

This invention relates to semiconductor lasers, and more particularly, to a cooling module for fabricating a liquid-cooled semiconductor laser, a fabricating method, and a semiconductor laser fabricated from the module, wherein the cooling module for a laser makes use of a liquid cooling plate provided with radiating fins to cool the semiconductor chip. After replacement of the traditional micro-channel structure with the radiating fin structure, the present invention effectively reduces the resistance to flow of the cooling liquid, remarkably lowers the pressure decrease of the cooling liquid, makes it easier to seal the cooling liquid, provides stronger heat dissipating capability, effectively elongates the lifetime of the semiconductor laser, and enhances the output power and reliability of the semiconductor laser, alongside the advantages of simple fabrication and low production cost.

FIELD OF THE INVENTION

The present invention relates to semiconductor lasers, and moreparticularly, to a cooling module for manufacturing a liquid-cooledsemiconductor laser, its fabricating method, and a semiconductor laserfabricated from the module.

BACKGROUND OF THE RELATED ART

A semiconductor laser is also referred to as the laser diode (LD). Sincethe eighties of the nineteenth century, technologies in semiconductorphysics have been greatly developed. Specifically, new technologies suchas the novel structures of the quantum well (QW) and the strainedquantum well (SL-QW), refractivity-modulated Bragg transmitter andmodulation-enhanced Bragg transmitter, especially, the new techniques ofMBE, MOCVD and CBE for the crystal growth and the new technique ofepitaxial growth, which can precisely control the crystal growth to theatomic layer thickness, have been developed. By taking advantages of thelatest development of technologies, it is possible to grow excellentquantum well materials and strained quantum well materials. As aconsequence, the LDs as fabricated had remarkably reduced thresholdcurrency, greatly enhanced conversion efficiency, times-fold increasedoutput power, and apparently elongated lifetime. With the continuingimprovements in stability, conversion efficiency and output power ofsemiconductor lasers, high-power semiconductor lasers have been found inincreasingly wider applications in industry, medicine and military,therefore, in great need in the market, and have shown ever broaderprospect for future development.

With the continuing and rapid development of the more and moreapplications of lasers, stricter and stricter requirements, by thevarious fields, have been raised to high-power semiconductor lasers,requiring them to be further improved in terms of output light power,conversion efficiency, reliability and performance stability. Inaddition to the chips, the performance of lasers is related to heatdissipation and packaging. In order to improve reliability andperformance stability and to lower production cost of lasers, highlyreliable packaging structures and highly effective heat-dissipatingstructures, on the one hand, and simplicity and cost effective, on theother hand, have always been pursued in the design and manufacture ofsemiconductor lasers.

Currently, there are two packaging modes for high-power single-arraysemiconductor layers, i.e. thermal-conduction cooling type (MichaelLeers, Konstantin Boucke, Manfred Gotz, et al., Thermal resistance independence of diode laser packages, In: Mark S. Zediker eds. Proceedingsof 56 SPIE, 2008. 6876 (687609)) and micro-channel liquid cooling type(Rushikesh M. Patel, David K. Wagner, Allen D. Danner, Kam Fallahpour,Richard S. Stinnett, “Use of micro-channel cooling for high-powertwo-dimensional laser diode arrays”, SPIE, vol. 634:466-474 (1992)).

While working under the mode of continuous wave, a laser ofthermal-conduction cooling type shall have a large block heat sink.Since a passive heat-dissipating mode is employed, this kind of lasertends to have temperature rising, which, in turn, leads to wavelengthshift of the laser and reduction in lifetime and reliability of thelaser. Consequently, its output power is usually a mere tens of watts.The passive heat-dissipating mode makes it very difficult for the poweroutput of the semiconductor laser to rise from tens of watts to hundredsof watts.

The micro-channel liquid cooling type has currently been in commercialproduction. Although active heat dissipation is employed in this type oflaser to have enhanced the heat-dissipating capability and greatlyincrease the power output of the laser, it has the following defects:

1. High Costs in Use and Maintenance

A micro-channel liquid cooler needs to use deionized liquid as coolingliquid in order to prevent the positive and negative electrodes fromelectric conduction. Moreover, low electrical conductivity of thedeionized liquid must be maintained throughout the period of use, sothat the costs in use and maintenance are very high.

2. Difficulty in Processing

The micro-channel liquid cooler is usually formed by copper materials,which are made by stacking several very thin layers of copper sheets oneon the other. The inner diameter of the micro through-channel is about300 microns. During the processing the micro-channel liquid cooler, eachlayer of copper sheets should be finely processed, so as to create aturbulent flow with high heat-dissipating capability when the liquidflows through the stacked micro through-channel. But, the fineprocessing of the micro-channel cooler is a difficult task.

3. High Production Cost

Since the fine processing of the micro-channel cooler is considerablydifficult, the production cost thereof is correspondingly very high.

4. Short Lifetime

During the process of operation of the laser, if impurities are presentin the cooling medium (which is usually deionized liquid), theseimpurities tend to attach on the inner wall of the micro channel. On theone hand, particles of these impurities might block the liquid passageof the micro-channel cooler to thereby reduce the cooling effect, thusgenerating relatively severe heat concentration that leads to shift ofthe output wavelength of the laser, broadening of the spectrum,reduction in performance reliability and lifetime, and in extreme case,even to burn out the laser. On the other hand, particles of theseimpurities would cause electrochemical erosion of the wall of the microchannel, and might erode away the wall of the micro-channel cooler insome cases, thus severely affecting the safety of the laser. All theseseriously and adversely affect the lifetime of the laser.

5. High Requirement on Sealing

Since the cooling medium flows in a very restricted space inside themicro-channel cooler, undesired pressure decrease is easily generated,whereby flow resistance of the cooling medium is high and sealing isdifficult.

In view of the above problems, it is apparent that currently availableliquid-cooled lasers as those discussed above are yet to be improved dueto inconveniences and deficiencies in structure, in manufacture, and inuse. To solve the aforementioned problems in the prior-art liquid-cooledlasers, manufacturers concerned tried their best to research for bettersolutions, but none of the designs, which have been developed andcompleted, has been found applicable until now for long. Solutions tothese problems have been eagerly sought by those concerned. Therefore,it is indeed one of the important tasks of research and development, aswell as an objective in urgent need for improvement in the art, todesign a practical, conveniently maintainable, structurally simple,manufacture cost-effective liquid-cooling laser.

In view of the aforementioned defects present in currently availableliquid-cooling lasers, the present inventor based on his experiences andprofessional knowledge acquired through years-long design andfabrication of such products, actively studied, constantly innovated andapplied relevant theories, tried to create a novel-structured, andimproved liquid-cooling laser with practical applicability. Afterincessant researches, designs, repeated trail productions of samples,and improvements, the present practically valuable invention has beenfinally made.

SUMMARY OF THE INVENTION

Aiming at overcoming the defects inherent in currently availableliquid-cooling lasers, a primary objective of the present invention isto provide a novel-structured cooling module used in a liquid-coolinglaser, a fabricating method thereof, and a semiconductor laserfabricated from such a module. The technical problems to be solved areto lower production cost, to reduce thermal resistance of such asemiconductor laser while the requirement of use power are satisfied, toremove the difficulty of unduly large pressure decrease of the coolingmedium, and to guarantee high output power of the laser on conditionthat the beam quality is satisfied.

The objective of and technical problems solved by the present inventionare realized by use of the following technical solutions.

Proposed according to the present invention is a cooling module for alaser, which includes a connection plate and a liquid cooling plate.Fixing holes are provided perpendicularly at central portions of theconnection plate and the liquid cooling plate. Liquid inlets and liquidoutlets are provided respectively at both adjacent sides of the fixingholes. A radiating fin is provided within the liquid inlet of the liquidcooling plate. A chip mounting area is reserved at one end of the liquidcooling plate close to the liquid inlet thereof. A heat sink and a chipare provided at the chip mounting area of the liquid cooling plate, withthe heat sink attaching to a positive electrode surface of the chip, anda negative electrode surface of the chip attaching to the connectionplate. An insulating plate is further provided between the connectionplate and the liquid cooling plate.

The cooling module for a laser as proposed in the present invention isfurther realized by use of the following technical means.

In the aforementioned cooling module for a laser, the liquid coolingplate, having a thickness of 1.6 mm, is made of metal, ceramic, diamond,or a composite material of copper and diamond.

In the aforementioned cooling module for a laser, the fixing hole has adiameter of 3.5 mm, the liquid inlet has a diameter of 5.5 mm, and theliquid outlet has a diameter of 5.5 mm.

In the aforementioned cooling module for a laser, the radiating fins ofthe liquid cooling plate are a plurality of metal leaves orhoneycomb-shaped liquid cooling checks fixed inside the liquid inlet.

The present invention further provides a method for fabricating theaforementioned cooling module for a laser. The method includes thefollowing steps of:

1) first making a liquid cooling plate into a rectangular plate,polishing the surface of the liquid cooling plate, and providing afixing hole and a liquid outlet thereon;2) providing a liquid inlet and radiating fins on the liquid coolingplate, and reserving a chip mounting area at an end of the liquidcooling plate close to the liquid inlet;3) providing sink holes at upper ends of the liquid outlet and theliquid inlet, thus completing fabrication of the liquid cooling plate;4) cleaning and drying the liquid cooling plate, thereafterelectroplating the liquid cooling plate to prevent corrosion; and5) using a patching process to patch a positive electrode of a chip ontoa heat sink by way of welding with a hard solder; then welding togetherthe heat sink, the chip and an insulating plate with a micro liquidcooling plate and a copper connection plate using a reflow solderingprocess; or connecting the chip with the liquid cooling plate with asoft solder if there is no step in the chip mounting area of the liquidcooling plate.

The present invention further proposes a single-bar semiconductor laserusing the aforementioned cooling module. The laser comprises a coolingmodule with a chip, an upper liquid cooling block, a positive electrodeconnection plate, a connection plate fixing plate, and a lower liquidcooling block, wherein the lower liquid cooling block, the coolingmodule and the upper liquid cooling block are connected to one anotherby stacking in the order from bottom to the top. A step is provided atone side of an upper surface of the lower liquid cooling block, and apositive electrode connection plate having a liquid outlet and aconnection plate fixing plate having a liquid outlet are provided on thestep. Corresponding to the fixing hole, the liquid inlet and the liquidoutlet of the cooling module, a fixing hole, a liquid inlet and a liquidoutlet on the lower cooling block are respectively provided.Corresponding to the fixing hole, the liquid inlet and the liquid outletof the cooling module, a fixing hole, a liquid inlet and a liquid outletof the upper cooling block and a communication hole communicating theupper cooling block liquid inlet and the upper cooling block liquidoutlet are respectively provided on the upper liquid cooling block. Thecooling module and the upper liquid cooling block and the lower liquidcooling block at the upper or lower sides of the cooling module arefixed together into an integrity, by a bolt passing through the fixingholes on the lower liquid cooling block and the cooling module to bescrewed into a threaded hole on the bottom of the upper liquid coolingblock. The liquid inlet of the lower cooling block, the liquid inlet ofthe cooling module and the liquid inlet of the upper cooling block forma liquid inflow passage, and the liquid outlet of the upper coolingblock, the liquid outlet of the cooling module, the liquid outlet of thepositive electrode connection plate, the liquid outlet of the connectionplate fixing plate, and the liquid outlet of the lower cooling blockform a liquid outflow passage.

In the aforementioned single-bar semiconductor laser, the liquid inletof the lower liquid cooling block consists of a lower liquid inlet, amiddle transition stepped hole and an upper expanded hole, and a sealring is provided at an orifice of the upper expanded hole.

The present invention further proposes a horizontal array typesemiconductor laser using the aforementioned cooling module. The lasercomprises a lower liquid cooling block, a positive electrode connectionplate, a negative electrode connection plate, an upper liquid coolingblock, and two or more cooling modules provided with fixing holes,liquid inlets, liquid outlets and chips arranged in parallel, whereinthe lower liquid cooling block is provided therein with a horizontalliquid inlet and a horizontal liquid outlet; two or more sets of liquidinlets and outlets are provided at the upper surface of the lower liquidcooling block, each set including a vertical liquid inlet and a verticalliquid outlet, of which the vertical liquid inlet is communicative withthe horizontal liquid inlet of the lower liquid cooling block, and thevertical liquid outlet is communicative with the horizontal liquidoutlet of the lower liquid cooling block; the two or more coolingmodules provided with liquid inlets and liquid outlets are disposed inparallel corresponding to each set of liquid inlets and liquid outletson the upper surface of the lower liquid cooling block, and the liquidinlet and the liquid outlet of each cooling module are respectivelycommunicative with the each set of the vertical liquid inlet and thevertical liquid outlet of the lower liquid cooling block; a positiveelectrode connection plate is provided between each cooling module andthe lower liquid cooling block, and a negative electrode connectionplate is provided on each cooling module; the upper liquid cooling blockis above the negative electrode connection plate; a bolt through-holecorresponding to the fixing hole at the central portion of the coolingmodule is provided on of the negative electrode connection plate; agroup of vertical bolt through-holes matching the corresponding fixingholes of the cooling modules is provided on the lower cooling block; areturn-liquid communication hole is provided in the upper liquid coolingblock; a liquid inlet and a liquid outlet are provided on a lowersurface of the upper liquid cooling block, and the liquid inlet and theliquid outlet of the upper liquid cooling block are communicative withthe return-liquid communication hole; a fixing screw hole is furtherprovided on the lower surface of the upper liquid cooling block; thelower liquid cooling block, the cooling module and the negativeelectrode connection plate are fixed on the upper liquid cooling blockvia a bolt.

The horizontal array type semiconductor laser as proposed in the presentinvention can be further realized by use of the following technicalmeans.

In the aforementioned horizontal array type semiconductor laser, thenegative electrode connection plate and the positive electrodeconnection plate, which are respectively provided at the upper and lowersides of each cooling module, are both fixed in insulation on the lowerliquid cooling block, wherein the negative electrode connection plate ofeach cooling module is connected with the positive electrode connectionplate of the adjacent cooling module, thus that each set of negativeelectrode connection plate and positive electrode connection plate atupper and lower sides of each cooling module forms a seriallyelectrically connected form, the negative electrode connection plate islead out by a negative electrode leading plate, and the positiveelectrode connection plate is lead out by a positive electrode leadingplate.

In the aforementioned horizontal array type semiconductor laser, a sinkgroove is provided at an upper opening of the vertical liquid inlet onthe lower liquid cooling block, and a liquid-tight seal ring is providedon the sink groove.

The present invention still provides a stacked array type semiconductorlaser using the aforementioned cooling module. The laser comprises alower bottom plate, a positive electrode block, a multi-bar seriallyconnected module set, a negative electrode block, an upper pressingblock, and a liquid cooling block stacked in the order from bottom up,wherein the multi-bar serially connected module set is formed bysequentially and perpendicularly stacking a plurality of cooling moduleshaving chips and provided with liquid inlets and liquid outlets; theliquid inlets and liquid outlets on the cooling modules form a liquidinflow passage and a liquid outflow passage of the multi-bar seriallyconnected module set; the positive electrode block is provided with apositive electrode block liquid inlet and a positive electrode blockliquid outlet thereon; the negative electrode block is correspondinglyprovided with a negative electrode block liquid inlet and a negativeelectrode block liquid outlet; the upper pressing block is provided witha liquid inlet and a liquid outlet thereon; the liquid cooling block isprovided with a liquid cooling block liquid inlet and a liquid coolingblock liquid outlet thereon; the positive electrode block liquid inlet,the liquid inflow passage of the positive electrode block, the negativeelectrode block liquid inlet, the liquid inflow passage of the negativeelectrode block, and the liquid cooling block liquid inlet aresequentially communicative with one another; the positive electrodeblock liquid outlet, the liquid outflow passage of the positiveelectrode block, the negative electrode block liquid outlet, the liquidoutflow passage of the negative electrode block, and the liquid coolingblock liquid outlet are sequentially communicative with one another; thelower bottom plate is correspondingly provided with a lower bottom plateliquid inlet and a lower bottom plate liquid outlet; and side plates areprovided at both sides of the lower bottom plate; the positive electrodeblock, the multi-bar serially connected module set and the negativeelectrode block are arranged between the two side plates standing up onthe lower bottom plate after having been sequentially stacked andmounted; the upper pressing block is disposed at an upper side of thenegative electrode block and is fixedly connected with the two sideplates of the lower bottom plate; an upper side face of the upperpressing block is fixedly connected with the liquid cooling block; acommunication hole is provided in the liquid cooling block, the liquidcooling block liquid inlet and the liquid cooling block liquid outletare communicative at one end with each other via the communication holeand another end thereof is respectively connected with the liquid inletand the liquid outlet of the upper pressing block; and the lower bottomplate, the positive electrode block, the multi-bar serially connectedmodule set, the negative electrode block and the upper pressing blockare connected together in the form of a stacked array via a boltcentrally passing therethrough.

In the aforementioned stacked array type liquid-cooled semiconductorlaser, an H-shaped rear plate is fixedly connected at a side of the twoside plates of the lower bottom plate, which is farer away from a lightemitting surface.

The present invention possesses apparent advantages and advantageouseffects in comparison with prior art technology. By virtue of thetechnical solutions discussed above, the cooling module for a laser, thesemiconductor laser fabricated from this module, and the fabricationmethod thereof according to the present invention achieve considerabletechnical progress and practical applicability, are highly valued forwidely industrial applications, and possess, at least, the advantagesspecified below.

1. The cooling module for a laser and the semiconductor laser fabricatedfrom this module according to the present invention are structurallysimple and convenient in operation and maintenance. Because of notadopting micro-channel structure but a radiating fin structure in theliquid cooling plate, the restriction of the size of the particles inthe cooling liquid is not highly required. Merely industrial water meetsthe requirement of normal operation. Moreover, it is easy tomechanically process the cooling module for a laser and thesemiconductor laser fabricated from this module, and the production costis relatively lower, whereby the cost can be greatly lowered whileeconomic efficiency is greatly enhanced. In terms of practicalapplicability and cost effect, the laser meets, by all means, therequirement for industrial development and is highly valued forindustrial application.

2. The cooling module for a laser and the semiconductor laser fabricatedfrom this module according to the present invention have greatheat-dissipating capabilities. The use of liquid cooling and the use ofa plurality of radiating fins in liquid passages to dissipate heat makeit possible to greatly increase in the heat-dissipation space of theliquid cooling plate, and creates stronger turbulence of the coolingmedium, thereby strengthening the cooling effect of the liquid coolingplate. Meantime, flowing space of the cooling medium is also increased,thereby achieving the functions of reducing flow resistance, reducingpressure decrease, reducing thermal resistance of the device andenhancing heat dissipation performance.

3. The cooling module for a laser and the semiconductor laser fabricatedfrom this module according to the present invention are highly reliable.Since the size of the water passage is greatly enlarged in comparisonwith the size of the micro-channel structure, the risk for the coolingliquid passage to be corroded is relatively low, hence reliability beinggreatly enhanced.

4. The cooling module for a laser and the semiconductor laser fabricatedfrom this module according to the present invention have less strictrequirements on sealing. Replacement of micro channel in the prior-artwith the radiating fins of the present invention greatly increases theflowing space for the cooling medium, and this, in turn, reduces theflow resistance and the pressure decrease, so that the requirement onsealing is consequently reduced.

5. The cooling module for a laser and the semiconductor laser fabricatedfrom this module according to the present invention make it possiblethat the power output of the laser and the liquid cooling capabilitycompletely satisfies the operating requirements of low duty-ratioquasi-continuous wave, and the laser realizes high power output.

6. The positions of its inlet and outlet of the cooling medium of thesemiconductor laser according to the present invention are changeable.They can be optionally designed to locate on the same end surface or ontwo different end surfaces, or on each end of the positive and negativeelectrode blocks.

7. The horizontal array type semiconductor laser according to thepresent invention employs the active heat dissipation mode, whereby theliquid directly rushes to the bottom of the heat-generating section ofthe laser, namely, the heat sink, to quickly carry away the heat, thusgreatly enhancing the heat dissipating capability of the array laser.The good heat dissipating capacity makes easy to raise the power, innecessity, to meet the requirement on high power as demanded by thelateral pump or special purposes of application. Since the fabricationprocess adopts individually packaging and assembling each laser (with acooling module having its chip), each laser can be separately fabricatedand is independent from others. If a single laser is damaged, it can beimmediately replaced without affecting other lasers from normaloperation, hence reducing the cost of operation of the entire horizontalarray laser. The number of lasers of the horizontal array can bemultiplied, thus making it possible to achieve even higher laser poweroutput, and making possible the operation under the continuous wave (CW)mode and the quasi-continuous wave (QCW) mode.

8. The stacked array type semiconductor laser according to the presentinvention realizes high power laser output. The reason is because astructure of a plurality of stacked and chip-embedded cooling modules isused, therefore, its liquid cooling capability completely satisfying theoperating requirements of low duty-ratio quasi-continuous wave.Consequently, it realizes high power laser output.

In summary, the cooling module for a laser, the semiconductor laserfabricated from this module, and the fabrication method thereofaccording to the present invention possess the aforementioned variousadvantages and practical values. They are greatly improved in terms ofstructures and functions, represent remarkable technical progress,produce useful and practical effects, and have many improved andprominent efficiencies as compared with prior-art semiconductor lasers.Because of these, they suit, well, the operation and are valued for wideand various industrial applications. The present designs are, indeed,novel, progressive and practical.

The above description is merely directed to a generalization about thetechnical solutions of the present invention. In order to make clearerthe technical means of the present invention for implementationaccording to the contents of the Description, and to make, more apparentand comprehensible, the above and other objectives, characteristics andadvantages of the present invention, preferred embodiments areparticularly provided below for detailed explanation with reference tothe accompanying drawings.

EXPLANATIONS TO THE ACCOMPANYING DRAWINGS

FIG. 1 is a three-dimensional exploded view showing the outer appearanceof the assembling structures of the cooling module according to thepresent invention.

FIG. 2 is a three-dimensional schematic view showing the outerappearance of the assembling structures of the cooling module accordingto the present invention.

FIG. 3 is a three-dimensional schematic view showing thehoneycomb-shaped radiating flakes of liquid cooling plate of the coolingmodule according to the present invention.

FIG. 4 is a three-dimensional exploded view showing the single-barsemiconductor laser according to the present invention.

FIG. 5 is a three-dimensional view showing the single-bar semiconductorlaser according to the present invention.

FIG. 6 is a sectional view showing the upper liquid cooling block of thesingle-bar semiconductor laser according to the present invention.

FIG. 7 is a sectional view showing the lower liquid cooling block of thesingle-bar semiconductor laser according to the present invention.

FIG. 8 is a chart showing P-I curve of a single-bar 808 nm semiconductorlaser sample according to the present invention.

FIG. 9 is a three-dimensional exploded view showing the horizontal arraytype semiconductor laser according to the present invention.

FIG. 10 is a three-dimensional schematic view showing the lower coolingmodule in the horizontal array type semiconductor laser according to thepresent invention.

FIG. 11 is a sectional view showing the upper cooling module in thehorizontal array type semiconductor laser according to the presentinvention.

FIG. 12 is a three-dimensional schematic view showing the horizontalarray type semiconductor laser according to the present invention.

FIG. 13 is a schematic view showing heat dissipation of the horizontalarray type semiconductor laser according to the present invention.

FIG. 14 is a three-dimensional exploded view showing the stacked arraytype semiconductor laser according to the present invention.

FIG. 15 is a three-dimensional schematic view showing the liquid coolingblock in the stacked array type semiconductor laser according to thepresent invention.

FIG. 16 is a sectional view showing the liquid cooling block in thestacked array type semiconductor laser according to the presentinvention.

FIG. 17 is a three-dimensional view showing assembly of the stackedarray type semiconductor laser according to the present invention.

FIG. 18 is a sectional schematic view showing the flow direction of thecooling liquid passage of the stacked array type semiconductor laseraccording to the present invention.

FIG. 19 is a sectional schematic view showing a alternative solution forthe cooling liquid passage of the stacked array type semiconductor laseraccording to the present invention.

SPECIFIC EMBODIMENTS FOR CARRYING OUT THE INVENTION

To further enunciate the technical means and effects employed by thepresent invention to achieve the predetermined inventive objectives, thecooling module for a laser, the fabrication method thereof, thesemiconductor laser fabricated from the module as proposed in thepresent invention, as well as their specific embodiments, structures,features and effects are described in greater details below withreference to the accompanying drawings and preferred embodiments.

The aforementioned solutions and other technical contents, features andeffects of the present invention will become clearer by the followingdetailed description with reference to the preferred embodimentsillustrated in the accompanying drawings. By the description of thespecific embodiments it is possible to get further and specifiedcomprehension about how the technical means employed and effectsachieved by the present invention and how to realize the predeterminedinventive objectives. However, the accompanying drawings herein includedare merely directed to providing references and explanations, and shallnot be used to restrict the present invention.

Referring to FIGS. 1 and 2, a cooling module 10 for a laser according toa preferred embodiment of the present invention mainly includes aconnection plate 1 and a liquid cooling plate 2 stacked with theconnection plate 1. Fixing holes 3 are provided vertically at centralportions of the mutually stacked connection plate 1 and liquid coolingplate 2 (the one on the connection plate 1 is the fixing hole 3-1, andthe one on the liquid cooling plate 2 is the fixing hole 3-2), andliquid inlets 4 (4-1, 4-2) and liquid outlets 5 (5-1, 5-2) are provided,respectively, at both sides of the fixing holes 3. A radiating fin 6 isprovided within the liquid inlet 4-2 of the liquid cooling plate 2, anda chip mounting area is provided at one end of the liquid cooling plate2 close to the liquid inlet 4 of the liquid cooling module.Specifically, the chip mounting area is a processed step 13. A heat sink7 and a chip 8 are provided on the chip mounting area of the liquidcooling plate, wherein the heat sink 7 attaches to the positiveelectrode surface of the chip 8, and the negative electrode surface ofthe chip 8 attaches to the connection plate 1. An insulating plate 9 isfurther provided between the connection plate 1 and the liquid coolingplate 2. The heat sink 7 may optionally be eliminated, in which casethere is no need to provide any step at the chip mounting area, andconsequently the positive electrode surface of the chip 8 directlyattaches to the liquid cooling plate 2. Whether a heat sink should beprovided is decided on the desires of the user.

The liquid cooling plate 2 is of a rectangular plate shape, and may alsobe designed as any other shapes, like a polygonal shape, as practicallydemanded. The fixing hole 3-2 at the central portion of the liquidcooling plate 2 has a diameter of 3.5 mm. The thickness of the liquidcooling plate 2 is controlled at 1.6 mm. The liquid inlet 4-2 has adiameter of 5.5 mm, and the liquid outlet 5-2 has a diameter of 5.5 mm.The radiating fin 6 disposed inside the liquid inlet 4-2 is a pluralityof metal leaves radially fixed into the liquid inlet 4-2 (as shown inFIG. 2), and the number thereof can be plurality, for example, threeleaves. The radiating fin 6 can either be integrally processed with theliquid inlet 4-2 or subsequently fixed onto the inside of the liquidinlet 4-2. The structure of the radiating fin 6 is not restricted to theone type of metal leaves, as it may, optionally, be honeycomb-shapedliquid cooling checks 11 disposed inside the liquid inlet 4-2 (as shownin FIG. 3).

The heat sink 7 is made of a material having good thermal conductivity.Thus even although additional heat dissipating path of the chip 8 may beadded, the phenomenon of thermal stress concentration, which is due tomismatch of thermal expansion coefficients caused by directly weldingthe chip 8 onto the liquid cooling plate 2, is removed to a considerableextent.

To facilitate the placement of a seal ring, a sink hole 12 having adiameter larger than that of the liquid inlet 4-2 and that of the liquidoutlet 5-2 is provided at the upper end of the liquid inlet 4-2 and theupper end of the liquid outlet 5-2. A seal ring 13 is provided in thesink hole 12, so as to guarantee the performance of sealing between theliquid cooling plate and other component parts during formation of thesemiconductor laser. The shapes of the liquid inlet 4-2 and the liquidoutlet 5-2 according to the present invention is round (as shown in FIG.1), or other shapes which suit the circulation of the cooling liquid,for example, polygonal and elliptical shapes.

The material of the liquid cooling plate 2 can be selected from suchmetals having good thermally conducting capabilities as copper andaluminum, and can also be selected from ceramic, diamond or othercomposite materials, for instance, a composite material of copper withdiamond. Moreover, the surface of the liquid cooling plate 2 can becoated with an anticorrosion layer.

The present invention further provides a method for fabricating theaforementioned cooling module for a laser. The method includes thefollowing steps of:

1) first processing a liquid cooling plate into a rectangular plate,polishing the surface of the liquid cooling plate, and providing afixing hole and a liquid outlet thereon;2) processing a liquid inlet and a radiating fin on the liquid coolingplate, and reserving for a chip mounting area at an end of the liquidcooling plate close to the liquid inlet;3) processing a sink hole at upper end of the liquid outlet and a sinkhole at upper end of the liquid inlet, thus completing fabrication ofthe liquid cooling plate;4) electroplating the liquid cooling plate after cleaning and dryingthereof to prevent corrosion; and5) welding a positive electrode (p surface) of a chip onto a heat sinkwith a hard solder (an alloy of gold and tin) using a patching process;then welding together the heat sink, the chip and an insulating platewith a micro liquid cooling plate and a copper connection plate using areflow soldering process; and connecting the chip with the liquidcooling plate with a soft solder if there is no step in the chipmounting area of the liquid cooling plate.

Referring to FIGS. 1, 4, 5, 6 and 8, a single-bar semiconductor laserusing the aforementioned cooling module 10 as proposed in the presentinvention includes a cooling module 10 with a chip, an upper liquidcooling block 110, a positive electrode connection plate 120, aconnection plate fixing plate 130, and a lower liquid cooling block 140.The lower liquid cooling block 140, the cooling module 10 and the upperliquid cooling block 110 are connected to one another by stacking in theorder from bottom up. A step 141 is provided at one side of an uppersurface of the lower liquid cooling block 140, and the positiveelectrode connection plate 120 having a liquid outlet 121 and theconnection plate fixing plate 130 having a liquid outlet 131 areprovided on the step 141. Corresponding to the fixing hole 3, the liquidinlet 4 and the liquid outlet 5 of the cooling module 10, a fixing hole142, a liquid inlet 143 and a liquid outlet 144 are respectivelyprovided on the lower liquid cooling block 140. Corresponding to thefixing hole 3, the liquid inlet 4 and the liquid outlet 5 of the coolingmodule 10, a fixing screw hole 111, an liquid inlet 112, an liquidoutlet 113, and a communication hole 114 communicating the upper coolingblock liquid inlet 112 and the upper cooling block liquid outlet 113 arerespectively provided on the upper liquid cooling block 110. The coolingmodule 10 and the upper liquid cooling block 110 at the upper side ofthe cooling module 10 and the lower liquid cooling block 140 at thelower side of the cooling module 10 are fixed together as an integrityby a bolt passing through the fixing hole of the lower liquid coolingblock 140 and the fixing hole of the cooling module 10 to be screwedinto the threaded hole 111 in the upper liquid cooling block 110. Theliquid inlet 143 of the lower cooling block, the liquid inlet 4 of thecooling module 10 and the liquid inlet 112 of the upper cooling block110 form a liquid inflow passage. The liquid outlet 113 of upper coolingblock 110, the liquid outlet 5 of the cooling module 10, the liquidoutlet 121 and the liquid outlet 131 of the positive electrodeconnection plate 120 and the connection plate fixing plate 130, and theliquid outlet 144 of the lower cooling block 140 form a liquid outflowpassage.

The liquid inlet 143 of the lower liquid cooling block 140 consists of alower liquid inlet 1431, a middle transition stepped hole 1432 and anupper expanded hole 1433. A seal ring 150 is provided at an orifice ofthe upper expanded hole 1433, to ensure excellent sealing of the liquidinflow passage. To achieve excellent sealing effect, it is desirable toprovide seal rings between each pair of the liquid inlets and outlets,for instance, between the liquid inlet 4 and the liquid inlet 112,between the liquid outlet 144 and the liquid outlet 121, between theliquid outlet 121 and the liquid outlets 5, between the liquid outlet 5and the liquid outlet 113, etc. so as to achieve excellent sealingeffect of the entire liquid inflow passage and the liquid outflowpassage.

The positive electrode connection plate 120 is fixed by the connectionplate fixing plate 130 to a screw hole 145 on one side of the lowerliquid cooling block 140 via a fixing hole 122 and a fixing hole 132provided at sides of the positive electrode connection plate 120 and theconnection plate fixing plate 130 by means of a screw. Provided at theside of the upper liquid cooling block 110 is a negative electrodeconnection hole 113, which is a threaded hole and leads out the negativeelectrode by using a screw. Provided at the side of the upper liquidcooling block 110 and at a port of the communication hole is a sealingplug 160.

The novel single-bar liquid-cooled laser according to the presentinvention is fabricated as discussed below.

1) As shown in FIGS. 5 and 7, the upper liquid cooling block 110 and thelower liquid cooling block 140 are made by drilling holes on a copperblock.

2) The seal rings 150 are placed, respectively, at outer rings of theupper ports of the liquid inlet 143 and the liquid outlet 144 of thelower liquid cooling block 140, at the liquid inlet 4 and the liquidoutlet 5 of the cooling module 10, and at outer rings of the lower portsof the liquid inlet 112 and the liquid outlet 113 of the upper liquidcooling block 110, and the lower liquid cooling block 140, the coolingmodule 10, and the upper liquid cooling block 110 are stacked one on theother from bottom up.

3) A connection bolt is used to sequentially pass through the fixingholes at the central portions of the lower liquid cooling block 140 andthe cooling module 10 to be screwed into the threaded hole 111 on theupper liquid cooling block 110, whereby the component parts are closelyconnected to one another, thus forming the single-bar liquid-cooledlaser according to the present invention.

The working principle of this embodiment is as follows.

During operation, the positive electrode connection plate 120 and thenegative electrode connection hole 113 are applied with voltage. Thelaser chip 8 normally operates, and the heat generated during operationis carried away via circulatory flow of the cooling liquid. The coolingliquid enters via the liquid inlet 146 of the lower liquid cooling block140 (as shown in FIG. 7), and passes through a liquid inflow passagetransition section 147 into the liquid inlet 143 and then into theliquid inlet 4 of the cooling module 10. The cooling liquid forms aturbulent flow within the liquid inlet 143 of the lower liquid coolingblock 140. The liquid inlet 143 is filled full of the cooling liquid,and most of the heat generated by the chip 8 is carried away directlyfrom the lower surface of the liquid cooling plate 2 in the coolingmodule 10 attaching to the chip 8. The residual heat generated by thechip 8 is transmitted to the radiating fin 6 through the liquid coolingplate 2, and the cooling liquid is rushed onto the liquid cooling plate2 and the radiating fin 6, carrying away the heat from the radiating fin6. Subsequently, the cooling liquid sequentially passes through theinsulating plate 9, and the connection plate 1 into the liquid inlet 112of the upper liquid cooling block 110, into the liquid outlet 113 via aconnection hole 115, then through the liquid outlet 5 of the coolingmodule 10, and is finally expelled out via the liquid outlet 114 of thelower liquid cooling block 140. After the heat has been dissipated by awater cooler, the cooling liquid reenters the liquid inlet 146. Thecooling liquid is completely sealed in the liquid inflow passage and theliquid outflow passage to prevent leakage of coolant from damaging thesemiconductor laser.

Besides the aforementioned structure of the inlet and outlet locationsof the cooling medium according to the present invention, it is alsopossible to adopt the circulation of liquid inflow and outflow into andout of the upper liquid cooling block, only. Also possible is to designthe inlet and outlet locations of the cooling medium at the two ends ofthe upper and lower liquid cooling blocks, in which case the coolingliquid flows unidirectionally into the laser. The specific circulationform of the cooling liquid should be flexibly decided by the mountingmode of the laser and the settings of external fittings. The upperliquid cooling block and the negative electrode block according to thepresent invention can either be integrated with each other orindependent of each other.

According to the laser structure of the present invention, an 808 nm,250 W single-array liquid-cooling semiconductor laser is fabricated,whose various test results are given below.

(1) Shown in FIG. 8 is an L-I-V curve of an 808 nm single-arraysemiconductor laser sample, the highest output light power thereof is289.45 W.

(2) Under the working condition of a pulse at 250 A (400 Hz, 200 us),the test result of the 808 nm single-array semiconductor laser sample isas shown in FIG. 7. At this time, the laser has a threshold current of21.35 A, a slope efficiency of 1.31 W/A, and a typical electro-opticconversion efficiency of 59.07%.

(3) The semiconductor laser sample as shown in FIG. 8 is fabricatedaccording to the present invention. It has a wavelength of 808 nm, apower of 250 W by a spectral test result, a peak wavelength of 808.53nm, a central wavelength of 808.53 nm, an FWHM of 2.73 nm, and an FW90%E of 3.85 nm.

The present invention Has changed the micro-channel liquid cooling formemployed by traditional semiconductor lasers under the condition ofsatisfying the requirement of use power. The present inventioneffectively avoids the deficiencies concerning the processing difficultyand high production cost brought about by processing the micro-channelstructure. By the use of fins to dissipate heat, the present inventionnot only reduces the resistance to circulation flow of the coolingliquid and avoids the defect of unduly large pressure decrease of thecooling liquid, but also greatly reduces the production cost due to thesimplified fabrication of the fins. Moreover, the mode of using fins todissipate heat achieves the same heat dissipating effect as the mode ofusing the micro-channel structure to dissipate heat. With thecooperation of the upper liquid cooling block and the lower liquidcooling block, the present invention achieves better heat dissipatingeffect.

Referring to FIGS. 9 to 13, a horizontal array type semiconductor laserusing the aforementioned cooling module as proposed in the presentinvention comprises a lower liquid cooling block 210, a positiveelectrode connection plate 220, a negative electrode connection plate230, an upper liquid cooling block 240, two or more cooling modules 10provided with fixing holes 3, liquid inlets 4, liquid outlets 5 andchips 8 arranged in parallel (see FIG. 1), as well as some auxiliarycomponent parts, such as watertight seal rings 270 and bolts or screwsas necessary. The lower liquid cooling block 210 is provided thereinwith a horizontal liquid inlet 211 and a horizontal liquid outlet 212,two or more sets (three sets shown in the drawings) of liquid inlets andoutlets are provided at an upper surface of the lower liquid coolingblock 210, each set including a vertical liquid inlet 213 and a verticalliquid outlet 214, of which the vertical liquid inlet 213 iscommunicative with the horizontal liquid inlet 211 of lower liquidcooling block 210, and the vertical liquid outlet 214 is communicativewith the horizontal liquid outlet 212 of lower liquid cooling block 210.The two or more cooling modules 10 provided with liquid inlets 4 andliquid outlets 5 are disposed in parallel corresponding to each set ofliquid inlets 213 and liquid outlets 214 on the upper surface of thelower liquid cooling block 210. The cooling module liquid inlet 4 andthe cooling module liquid outlet 5 of each cooling module 10 arerespectively communicative with the vertical liquid inlet 213 and thevertical liquid outlet 214 of each set of liquid inlets and liquidoutlets on the lower liquid cooling block 210. A positive electrodeconnection plate 220 is provided between each cooling module 10 and thelower liquid cooling block 210, and a negative electrode connectionplate 230 is provided on each cooling module 10. The upper liquidcooling block 240 is placed on top of the negative electrode connectionplate 230. A bolt through-hole 231 matching to the corresponding fixinghole 3 at the middle portion of the cooling module 10 is provided on thenegative electrode connection plate 230. A set of perpendicular boltthrough-holes 215 matching to the corresponding fixing hole 3 of eachcooling module 10 is provided on the lower liquid cooling block 210. Areturn-liquid communication hole 241 is provided in the upper liquidcooling block 240 (as shown in FIG. 11). The return-liquid communicationhole 241 in the upper liquid cooling block 240 is a blind hole whoseopening end is usually blocked by a stopper to prevent the coolingliquid from flowing out (not shown in the drawings). A liquid inlet 242and a liquid outlet 243 are provided on a lower surface of the upperliquid cooling block 240. The liquid inlet 242 of the upper liquidcooling block 240 and the liquid outlet 243 of the upper liquid coolingblock 240 are communicative with the return-liquid communication hole241. A fixing screw hole 244 is further provided on the lower surface ofthe upper liquid cooling block 240 in a position between the liquidinlet 242 of the upper liquid cooling block 240 and the liquid outlet243 of the upper liquid cooling block 240. The lower liquid coolingblock 210, the cooling module 10 and the negative electrode connectionplate 230 are fixed on the upper liquid cooling block 240 via a bolt.

The bolt through-hole 215 on the lower liquid cooling block 210 locatesbetween the vertical liquid inlet 213 and the vertical liquid outlet 214of each set of liquid inlets and outlets. A step is provided on thelower liquid cooling block 210 at the surface where the vertical liquidoutlet 214 is located.

The negative electrode connection plate 230 and the positive electrodeconnection plate 220, which are respectively provided at the upper orlower sides of each cooling module 10, are both fixed in insulation onthe lower liquid cooling block 210. The negative electrode connectionplate 230 of each cooling module 10 is connected with the positiveelectrode connection plate 220 of the adjacent cooling module 10, thusthat each set of negative electrode connection plate 230 and positiveelectrode connection plate 220 at upper or lower sides of each coolingmodule 10 forms an electrical series connection. The negative electrodeconnection plate 230 is lead out by a negative electrode leading plate250, and the positive electrode connection plate 220 is lead out by apositive electrode leading plate 260. The shape of the negativeelectrode connection plate 230 is designed according to the coolingmodule 10. Corresponding through-holes are provided on the negativeelectrode connection plate 230 in a position according to the pattern ofthe cooling module 10, on which, the liquid inlet 4, the liquid outlet5, and the fixing hole 3 exist. The positive electrode connection plate220 is a small piece of metal plate, and is provided with a through-holecorresponding to the liquid outlet 5 of the cooling module 10.

In order to increase the turbulence level of the cooling liquid insidethe vertical liquid inlet 213 on the lower liquid cooling plate 210, asink groove 216 is provided at an upper opening of the vertical liquidinlet 213 on the lower liquid cooling block 210. The sink groove 216 maybe set as a rectangular shape, as shown in the drawings, or may bedesigned in any other shapes upon practical demand. The diameter of thesink groove 216 is larger than that of the vertical liquid inlet 213. Aseal ring 270 is provided on the sink groove 216. A step is processed atthe edge of the sink groove 216, and the seal ring 270 is mounted onthis step.

The specific mounting structure of this embodiment is as follows. Two ormore (three as shown in the drawings) cooling modules 10 independentfrom one another are arranged in parallel on the upper surface of thelower liquid cooling block 210 and correspondingly to each set of liquidinlets and outlets on the lower liquid cooling block 210. The positiveelectrode connection plate 220 is disposed between each cooling module10 and the lower liquid cooling plate 210, and the negative electrodeconnection plate 230 is disposed on each cooling module 10. The upperliquid cooling plate 240 is disposed on each negative electrodeconnection plate 230. The liquid inlet 4 and the liquid outlet 5 of eachcooling module 10 are respectively communicative with the verticalliquid inlet 213 and the vertical liquid outlet 214 of each set ofliquid inlets and liquid outlets on the lower liquid cooling block 210.At the same time, the liquid inlet 4 and the liquid outlet 5 of eachcooling module 10 are also respectively communicative with the upperliquid cooling block liquid inlet 242 and the upper liquid cooling blockliquid outlet 243 on the upper liquid cooling plate 240. The sink groove216 on the vertical liquid inlet 213 of each set of liquid inlets andoutlets on the lower liquid cooling block 240 is located below thecooling module 10, and attaches to the liquid cooling plate 2 of thecooling module 10 via the watertight seal ring 270. The positiveelectrode connection plate 220 is mounted on the step on a surface wherethe vertical liquid outlet 214 of the lower liquid cooling block 210 islocated, and each positive electrode connection plate 220 respectivelyattaches to the underside of the liquid cooling plate 2 of each coolingmodule 10. The first positive electrode connection plate 220 is directlyconnected with the positive electrode leading plate 260, the nextpositive electrode connection plate 220 is connected with the previousnegative electrode connection plate 230, each negative electrodeconnection plate 230 attaches to the connection plate 1 on each coolingmodule 10, and each negative electrode connection plate 230 is connectedwith the next positive electrode connection plate 220, that is to say,each set of negative electrode connection plate 230 and positiveelectrode connection plate 220 at upper and lower sides of each coolingmodule 10 forms a serially electrically connected form. The lastnegative electrode connection plate 230 of the cooling module isdirectly lead out by the negative electrode leading plate 250. Eachpositive electrode connection plate 220 and each corresponding negativeelectrode connection plate 230 are both fixed via bolts on a set ofconnection plate fixing holes 217 at a side of the lower liquid coolingplate 210, and an insulating plate 280 for insulation is providedbetween each set of positive electrode connection plate 220 and negativeelectrode connection plate 230.

The upper liquid cooling block 240, the cooling module 10 and thenegative connection plate 230 are fixed via bolts on the lower liquidcooling block 210. Specifically, the bolts pass through the lower end ofthe screw fixing hole 215 on the lower liquid cooling block 210, thensequentially pass through the bolt through-holes of the cooling module10 and that of the negative electrode connection plate 230, and arefinally screwed into the upper liquid cooling block fixing screw hole244 at the lower end of the upper liquid cooling block 240. To ensuresealing property, rubber seal rings 13 are provided on both the liquidinlet 4 and the liquid outlet 5 of the cooling module 10 according tothe present invention.

The fabrication process of this embodiment is as follows:

(1) Opening holes on the lower liquid cooling block 210, in which theholes' diameters of the lower liquid cooling block horizontal liquidinlet 211 and the lower liquid cooling block horizontal liquid outlet212 should be made slightly larger than the holes' diameters of theliquid inlet 4 and larger than that of the liquid outlet 5 of thecooling module 10 to ensure stable water flow;

(2) first placing N number of watertight seal rings 270 at the verticalliquid inlet 213 of the lower liquid cooling block 210, then placing thepositive electrode connection plate 220 on the lower liquid coolingblock 210, and subsequently arranging in parallel thereon N number ofcooling modules 10 with chips 8; thereafter, sequentially stacking thenegative electrode connection plate 230 and the upper liquid coolingblock 240 above the cooling modules 10, clamping the positive electrodeleading plate 260 below the outermost positive electrode connectionplate 220, and sequentially fixing the positive electrode connectionplate 260, the previous negative electrode connection plate 230, theinsulating plate 280, and the negative electrode leading plate 230 ofthe cooling modules 10 to the edge of the lower liquid cooling block 210in an outward order; wherein the negative electrode connection plate 230and the positive electrode connection plate 220 are separated from eachother by means of the insulating plate 280, and are fixed onto the lowerliquid cooling block 210 by means of fixing screws to ensure reliabilityof the electrical connection. Finally, the entire structure is connectedby bolts;

(3) testing, to ensure that various parameters and indices conform toex-factory qualifications.

The operating procedures of this embodiment is as follows.

A p-n junction semiconductor luminescent material connected at thepositive and negative electrodes of the chip 8 is applied with a forwardbias, where the p-region is connected to the positive electrode, and then-region is connected to the negative electrode. The electric field ofthe forward voltage is reverse in direction to the self-establishedelectric field of the p-n junction, thus weakening the resistancefunction of the self-established electric field against the diffusionmovement of electrons in the crystals, whereby free electrons in then-region incessantly diffuse through the p-n junction towards thep-region under the action of the forward voltage. Moreover, when greatquantities of electrons in the conduction band and holes in the valenceband are present in the joint region, they will be compounded in theinjection region. When electrons in the conduction band transition tothe valence band, redundant energy will be emitted out in the form oflight. Heat generated during operation of the laser is dissipated bymeans of the liquid cooling plate 2 in the cooling module 10. Referringto FIG. 13, the cooling liquid enters via the horizontal liquid inlet211 of the lower liquid cooling block 210 into each vertical liquidinlet 214, abruptly expands in the sink groove 216, contacts, in a largearea, the underside surface of the cooling module 10 where the chip ismounted, then absorbs the heat generated by the operation of the chip 8from the liquid inlet 4 of each cooling module 10 through the radiatingfin 6, subsequently flows upwards into the liquid inlet 242 of the upperliquid cooling block 240, enters each vertical liquid outlet 214 afterflowing through the cooling module liquid outlet 5 via the return-liquidcommunication hole 241 and the liquid outlet 243 of the upper liquidcooling block, and is finally expelled to carry away the heat afterconverging at the horizontal liquid outlet 212 of the lower liquidcooling block 210.

In comparison with a micro-channel liquid-cooled semiconductor laserarray product, the product according to this embodiment greatly reducesthe production cost and decreases the thermal resistance on conditionsof satisfying the requirements of use power and duty ratio, removes theproblem of unduly large pressure decrease of the cooling medium, andguarantees high output power on the precondition of satisfying thedemand on beam quality.

The technical solution of this embodiment is neither restricted to whatis described above, nor to the structural forms illustrated in thedrawings accompanying the Description. Some substitute solutionsemployable by the present invention are listed as follows.

1. The liquid inlets and outlets of the entire semiconductor laser arenot limited to being disposed on the lower liquid cooling block 210, asit is also possible to dispose the liquid inlets on the lower liquidcooling block 210, and to dispose the liquid outlets on the upper liquidcooling block 240.

2. The liquid inlets and outlets on the lower liquid cooling block 210can be either located at the same side or located at the left and rightsides. There can be either only one liquid inlet and one liquid outlet,or more than one liquid inlets and liquid outlets.

3. The cooling liquid passages (such as the vertical liquid inlet, thevertical liquid outlet, the cooling module liquid inlet, and the coolingmodule liquid outlet, etc.) on the lower liquid cooling block 210 andthe cooling module 10 can have any shapes of cross-sections, such asrectangular shape, elliptical shape, and so on.

4. The upper liquid cooling blocks 240 can either be independent fromthe cooling modules 10, or match the cooling modules 10 on a one-to-onebasis, or fix together with the cooling modules 10 into an integrity.The upper liquid cooling block 240 can be made either of a metal or of anon-metallic material.

Referring to FIGS. 14-19, the present invention further provides astacked array type semiconductor laser using the aforementioned coolingmodule. The laser comprises a lower bottom plate 310, a positiveelectrode block 320, a multi-bar serially connected module set 330, anegative electrode block 340, an upper pressing block 350, and a liquidcooling block 360 stacked in the order from bottom up, wherein themulti-bar serially connected module set 330 is formed by sequentiallyand perpendicularly stacking a plurality of cooling modules 10 (seeFIG. 1) having chips 8 and provided with liquid inlets 4 and liquidoutlets 5.

The liquid inlets 4 and liquid outlets 5 on the cooling modules 10 forma liquid inflow passage 331 and a liquid outflow passage 332 of themulti-bar serially connected module set, and the liquid inflow passage331 and the liquid outflow passage 332 are perpendicular to planes ofthe cooling modules 33 having chips. Radiating fins 6 are provided atintervals within passages inside the liquid inflow passage 331.

The positive electrode block 320 is provided with a liquid inlet 321 anda liquid outlet 322 thereon, and with a through-hole 323 interposedtherebetween. The negative electrode block 340 is correspondinglyprovided with a liquid inlet 341 and a liquid outlet 342. The upperpressing block 350 is provided with a liquid inlet 351 and a liquidoutlet 352 thereon. The liquid cooling block 360 is provided with aliquid inlet 361 and a liquid outlet 362 thereon. The positive electrodeblock liquid inlet 321, the liquid inflow passage 331, the negativeelectrode block liquid inlet 341, the liquid inflow passage 351, and theliquid cooling block liquid inlet 361 are sequentially communicativewith one another, and the positive electrode block liquid outlet 322,the liquid outflow passage 332, the negative electrode block liquidoutlet 342, the liquid outflow passage 352, and the liquid cooling blockliquid outlet 362 are sequentially communicative with one another. Thelower bottom plate 310 is correspondingly provided with a liquid inlet311 and a liquid outlet 312. Side plates 313 are provided at both sidesof the lower bottom plate. The positive electrode block 320, themulti-bar serially connected module set 330 and the negative electrodeblock 340 are sequentially stacked and mounted and thereafter arrangedbetween the two side plates 313 standing on the lower bottom plate 310.The cooling module 10 at the bottom of the multi-bar serially connectedmodule set 330 closely attaches to the positive electrode block 320, andthe lower ports of the liquid inflow passage 331 and the liquid outflowpassage 332 are respectively connected via seal rings with the positiveelectrode block liquid inlet 321 on the positive electrode block 320 andthe upper port of the positive electrode block liquid outlet 322.

The upper pressing block 350 is disposed at the upper side of thenegative electrode block 340 and is fixedly connected with the upperends of the two side plates 313 of the lower bottom plate 310. An upperside face of the upper pressing block 350 is fixedly connected with theliquid cooling block 360.

The structure of the liquid cooling block 360 is shown in FIGS. 15 and16. A conduction hole 363 is disposed in the liquid cooling block 360,and a liquid cooling block liquid inlet 361 and a liquid cooling blockliquid outlet 362 are provided at a lower surface of the liquid coolingblock 360. The liquid cooling block liquid inlet 361 and the liquidcooling block liquid outlet 362 are communicative with each other viathe conduction hole 363, which is a blind hole having a stopper 364provided at its opening. Thus, the liquid inflow passage 331, theconduction hole 363 and the liquid outflow passage 332 of the multi-barserially connected module set 330 form a cooling medium circulation loop(as shown in FIG. 18).

The lower ports of the liquid inlet 351 and the liquid outlet 352 of theupper pressing block 350 are connected via seal rings with the upperports of the negative electrode block liquid inlet 341 and the negativeelectrode block liquid outlet 342 on the negative electrode block 340.The shape of the negative electrode block 340 is same as the shape ofthe positive electrode block 320, and the lower surface of the negativeelectrode block 340 attaches to the connection plate 1 of the coolingmodule 10 at the top of the multi-bar serially connected module set 330.The negative electrode block liquid inlet 341 and the negative electrodeblock liquid outlet 342 are also respectively connected via seal ringswith the liquid inflow passage 331 and the liquid outflow passage 332.

An H-shaped rear plate 380 is fixedly connected to the side of the twoside plates 313 of the lower bottom plate 310, which is farer from alight emitting surface of the multi-bar serially connected module set330. The H-shaped rear plate 380 is fixed on the side plate 313 via abolt by means of a rear plate fixing hole 381 disposed thereon. Thelower bottom plate 310, the positive electrode block 320, the multi-barserially connected module set 330, the negative electrode block 340 andthe upper pressing block 350 are connected together with the liquidcooling block 360 in the form of a stacked array via a bolt 370centrally passing therethrough, thus forming a complete liquid coolingclosed loop.

The specific fabrication method according to the present invention isdescribed in more details below:

1) processing connection holes 354 and 365 on the upper pressing block350 and the liquid cooling block 360;

2) fixedly fastening the H-shaped rear plate 380 via a bolts onto thetwo side plates 313 of the bottom plate 310 through the fixing hole 381;

3) coating an insulating layer on the lower surface of the positiveelectrode block 320, the side plates 313 and the H-shaped rear plate380; placing the positive electrode block 320 between the two sideplates 313 of the bottom plate 310, attaching one face of the insulatinglayer to the liquid inlet 311 of the lower bottom plate 310, and usingseal rings to seal the upper and lower sides of the liquid inlet 321 andthe liquid outlet 322 of the positive electrode block 320;

4) stacking a plurality of cooling modules 10 with chips in theperpendicular direction to form the multi-bar serially connected moduleset 330, placing the bottom end of the liquid cooling plate 2 of thelowermost cooling module 10 on the positive electrode block 320 having aseal ring, and abutting the entire multi-bar serially connected moduleset 330 against the rear plate 380;

5) coating an insulating layer on the upper surface of the negativeelectrode plate 340, and placing the negative electrode block 340 on thecopper connection plate 1 disposed on the top multi-bar seriallyconnected module set 330;

6) placing the upper pressing block 350 on the negative electrode block340, and using the through-bolt 370 to fixedly connect together theupper pressing block 350, the negative electrode block 340, themulti-bar serially connected module set 330, the positive electrodeblock 320, and the lower bottom plate 310;

7) using screws to fasten together the upper pressing block 350 with thetwo side plates 313 of the lower bottom plate 310 via a connection screw353 and a side plate fixing screw 314;

8) fixedly connecting the liquid cooling block 360 with a fixing screw354 on the upper pressing block 350 via the connection hole 365.

Finally as shown in FIG. 17, the entire stacked array is assembled frombottom to the top to become a complete stacked array type liquid-cooledsemiconductor laser.

The operating procedures of the stacked array type liquid-coolingsemiconductor laser according to this embodiment is described in moredetails below.

As shown in FIG. 18, during operation, the liquid cooling plate 2 andthe connection plate 1 of each cooling module 10 with a chip are appliedwith voltage. Since the p-region of the chip 8 is connected with theliquid cooling plate 2 and the n-region thereof is connected with theconnection plate 1, the p-n junction semiconductor material of the chip8 is applied with a forward bias. The electric field of the forwardvoltage is reverse in direction to the self-established electric fieldof the p-n junction, thus weakening the resistance function of theself-established electric field against the diffusion movement ofelectrons in the crystals, whereby free electrons in the n-regionincessantly diffuse through the p-n junction towards the p-region underthe action of the forward voltage. Moreover, when great quantities ofelectrons in the conduction band and holes in the valence band arepresent in the joint region, they will be compounded in the injectionregion. When electrons in the conduction band jump up to the valenceband, redundant energy will be emitted out in the form of light. Thelight emitted from each cooling module 10 with a chip is from thelateral direction of the chip 8.

The chip 8 generates great amount of heat during the process ofoperation, and circulatory flow of the cooling liquid as described belowis necessary to cool the chip 8.

The cooling liquid enters from the liquid inlet 311 of the lower bottomplate 310, and passes through the liquid inlet 321 of the positiveelectrode block 320 into the liquid inflow passage 331 of the multi-barserially connected module set 330 to carry away the heat from theradiating fins 6 in the liquid inflow passage 331. After flowing out ofthe liquid inflow passage 331, the cooling liquid passes through theliquid inlet 341 of the negative electrode block 340 and the liquidinlet 351 of the upper pressing block 350 into the liquid inlet 361 ofthe liquid cooling block 360, is guided by the conduction hole 363 toenter the liquid cooling block liquid outlet 362, thereafter leaves theliquid cooling block 360, enters the liquid outflow passage 332 of themulti-bar serially connected module set 330 through the liquid outlet352 of the upper pressing block 350 and the negative electrode blockliquid outlet 342, and reenters the liquid outlet 322 of the positiveelectrode block 320 to flow out of the liquid outlet 312 at the lowerend of the lower bottom plate 310. After passing through a water cooler,the cooling liquid reenters the liquid inlet at the lower end of thelower bottom plate 310, thus realizing the circulatory cooling functionof cooling liquid.

The cooling liquid of the laser cooling internal circulation pipe asshown in FIG. 14 or 17 or 18 flows in from the liquid inlet 311 at thelower end of the lower bottom plate 310 and flows out of the liquidoutlet 312 of the lower bottom plate 310. However, the present inventionis not restricted to this one solution, but it is also possible toprovide the liquid inlet of the cooling liquid on the lower bottomplate, and to provide the liquid outlet on the liquid cooling block 360,as shown in FIG. 19. In addition, the circulatory flowing direction ofthe cooling liquid can also be in from above while out from below.

In summary, besides simple fabrication and low production cost, afterreplacement of the traditional micro-channel structure with theradiating fin structure, the present invention effectively reduces theresistance to flow of the cooling liquid, remarkably lowers the pressuredecrease of the cooling liquid, makes it easier to seal the coolingliquid, provides stronger heat dissipating capability, effectivelyelongates the lifetime of the semiconductor laser, and enhances theoutput power and reliability of the semiconductor laser.

The above is merely descriptive of preferred embodiments of the presentinvention, rather than restrictive of the present invention in whicheverform. Although the present invention has been disclosed with theaforementioned preferred embodiments, these are not meant to restrictthe present invention. Any person skilled in the art may make use of thetechnical contents disclosed above to make slight variations ormodifications as equivalent embodiments without departing from the scopeof the technical solution of the present invention. However, any suchsimple amendments, equivalent variations and modifications made to theaforementioned embodiments according to the technical substance of thepresent invention and without departing from the technical solution ofthe present invention shall be covered by the scope of the technicalsolution of the present invention.

1. A cooling module for a laser, wherein the cooling module comprises aconnection plate and a liquid cooling plate, wherein fixing holes areprovided perpendicularly at central portions of the connection plate andthe liquid cooling plate, liquid inlets and liquid outlets are providedrespectively at both adjacent sides of the fixing holes, a radiating finis provided inside the liquid inlet of the liquid cooling plate, a chipmounting area is provided at one end of the liquid cooling plate closeto the liquid inlet thereof, a heat sink and a chip are provided at thechip mounting area of the liquid cooling plate, the heat sink attachesto a positive electrode surface of the chip, a negative electrodesurface of the chip attaches to the connection plate, and an insulatingplate is further provided between the connection plate and the liquidcooling plate.
 2. The cooling module for a laser according to claim 1,wherein the liquid cooling plate, having a thickness of 1.6 mm, is madeof metal, ceramic, diamond, or a composite material of copper anddiamond, having a thickness of 1.6 mm.
 3. The cooling module for a laseraccording to claim 1, wherein the fixing hole has a diameter of 3.5 mm,the liquid inlet has a diameter of 5.5 mm, and the liquid outlet has adiameter of 5.5 mm.
 4. The cooling module for a laser according to claim1, wherein the radiating fin of the liquid cooling plate is a pluralityof metal leaves or honeycomb-shaped liquid cooling checks fixed in theliquid inlet.
 5. The cooling module for a laser according to claim 1,wherein a seal ring is provided on an upper end of the liquid inlet ofthe liquid cooling plate.
 6. A method for fabricating the cooling modulefor a laser, wherein the method comprises the following steps of: 1)first processing a liquid cooling plate into a rectangular plate,surface-polishing the liquid cooling plate, and providing a fixing holeand a liquid outlet thereon; 2) processing a liquid inlet and aradiating fin on the liquid cooling plate, and reserving for a chipmounting area at an end of the liquid cooling plate close to the liquidinlet; 3) processing sink holes at upper ends of the liquid outlet andthe liquid inlet, thus completing fabrication of the liquid coolingplate; 4) electroplating the liquid cooling plate after cleaning anddrying thereof to prevent corrosion; and 5) welding a positive electrodeof a chip onto a heat sink with a hard solder using a patching process;then welding together the heat sink, the chip and an insulating platewith a micro liquid cooling plate and a copper connection plate using areflow soldering process; or connecting the chip with the liquid coolingplate with a soft solder in case there is no step in the chip mountingarea of the liquid cooling plate.
 7. A single-bar semiconductor laserusing the cooling module according to claim 1, comprising a coolingmodule with a chip, an upper liquid cooling block, a positive electrodeconnection plate, a connection plate fixing plate, and a lower liquidcooling block, wherein the lower liquid cooling block, the coolingmodule and the upper liquid cooling block are connected to one anotherby stacking them in the sequence from bottom to the top; a step isprovided at one side of the upper surface of the lower liquid coolingblock, and a positive electrode connection plate having a liquid outletand a connection plate fixing plate having a liquid outlet are providedon the step; corresponding to the fixing hole, the liquid inlet and theliquid outlet of the cooling module, a lower cooling block fixing hole,a lower cooling block liquid inlet and a lower cooling block liquidoutlet are respectively provided on the lower liquid cooling block;corresponding to the fixing hole, the liquid inlet and the liquid outletof the cooling module, a fixing screw hole, an upper cooling blockliquid inlet, an upper cooling block liquid outlet, and a communicationhole communicating the upper cooling block liquid inlet and the uppercooling block liquid outlet are respectively provided on the upperliquid cooling block; the cooling module, the upper liquid cooling blockat the upper side of the cooling module and the lower liquid coolingblock at the lower side of the cooling module are fixed together as anintegrity by a bolt, which passes through the fixing holes on the lowerliquid cooling block and the cooling module to be screwed into athreaded hole on the upper liquid cooling block; the liquid inlet of thelower cooling block, the liquid inlet of the cooling module and theliquid inlet of the upper cooling block form a liquid inflow passage;and the liquid outlet of the upper cooling module, the liquid outlet ofthe cooling module, the liquid outlets of the positive electrodeconnection plate and the connection plate fixing plate, and the liquidoutlet of the lower cooling module form a liquid outflow passage.
 8. Thesingle-bar semiconductor laser according to claim 7, wherein the liquidinlet of the lower liquid cooling block consists of a lower liquidinlet, a middle transition stepped hole and an upper expanded hole,wherein a seal ring is provided at an orifice of the upper expandedhole.
 9. A horizontal array type semiconductor laser using the coolingmodule according to claim 1, comprising a lower liquid cooling block, apositive electrode connection plate, a negative electrode connectionplate, an upper liquid cooling block, and two or more cooling modulesprovided with fixing holes, liquid inlets, liquid outlets and chipsarranged in parallel, wherein the lower liquid cooling block is providedtherein with a lower liquid cooling block horizontal liquid inlet and alower liquid cooling block horizontal liquid outlet, two or more sets ofliquid inlets and outlets are provided at an upper surface of the lowerliquid cooling block, each set including a vertical liquid inlet and avertical liquid outlet, the vertical liquid inlet being communicativewith the horizontal liquid inlet of the lower liquid cooling block, andthe vertical liquid outlet being communicative with the horizontalliquid outlet of the lower liquid cooling block; the two or more coolingmodules provided with liquid inlets and liquid outlets are disposed inparallel corresponding to each set of liquid inlets and liquid outletson the upper surface of the lower liquid cooling block, and the coolingmodule liquid inlet and the cooling module liquid outlet of each coolingmodule are communicative with the vertical liquid inlet and the verticalliquid outlet of each set of liquid inlets and liquid outlets on thelower liquid cooling block, a positive electrode connection plate isprovided between each cooling module and the lower liquid cooling block,a negative electrode connection plate is provided on each coolingmodule, and the upper liquid cooling block is disposed on the negativeelectrode connection plate; the negative electrode connection plate isprovided with a bolt through-hole in a position corresponding to thefixing hole at a middle portion of the cooling module; a the lowerliquid cooling block is provided with a set of perpendicular boltthrough-holes in a position corresponding to the fixing holes at eachcooling module; a return-liquid communication hole is provided in theupper liquid cooling block; an upper liquid cooling block liquid inletand an upper liquid cooling block liquid outlet are provided on a lowersurface of the upper liquid cooling block; the upper liquid coolingblock liquid inlet and the upper liquid cooling block liquid outlet arecommunicative with the return-liquid communication hole; a fixing screwhole is further provided on the lower surface of the upper liquidcooling block; and the lower liquid cooling block, the cooling moduleand the negative electrode connection plate are fixed on the upperliquid cooling block via a bolt.
 10. The horizontal array typesemiconductor laser according to claim 9, wherein the negative electrodeconnection plate and the positive electrode connection plate, which arerespectively provided at the upper and lower sides of each coolingmodule, are both fixed in insulation on the lower liquid cooling block,wherein the negative electrode connection plate of each cooling moduleis connected with the positive electrode connection plate of theadjacent cooling module, thus that each set of negative electrodeconnection plate and positive electrode connection plate at upper andlower sides of each cooling module forms a serially electricallyconnected form, the negative electrode connection plate being lead outby a negative electrode leading plate, and the positive electrodeconnection plate being lead out by a positive electrode leading plate.11. The horizontal array type semiconductor laser according to claim 9,wherein an enlarged oblong sink groove is provided at an upper openingof the vertical liquid inlet on the lower liquid cooling block, and aliquid-tight seal ring is provided on the sink groove.
 12. A stackedarray type semiconductor laser using the cooling module according toclaim 1, comprising a lower bottom plate, a positive electrode block, amulti-bar serially connected module set, a negative electrode block, anupper pressing block, and a liquid cooling block stacked in the abovesequence from bottom up, wherein the multi-bar serially connected moduleset is formed by sequentially and perpendicularly stacking a pluralityof cooling modules having chips and provided with liquid inlets andliquid outlets, the liquid inlets and liquid outlets on the coolingmodules form a liquid inflow passage and a liquid outflow passage of themulti-bar serially connected module set, the positive electrode block isprovided with a positive electrode block liquid inlet and a positiveelectrode block liquid outlet thereon, the negative electrode block iscorrespondingly provided with a negative electrode block liquid inletand a negative electrode block liquid outlet, the upper pressing blockis provided with a liquid inlet and a liquid outlet thereon, the liquidcooling block is provided with a liquid cooling block liquid inlet and aliquid cooling block liquid outlet thereon, the positive electrode blockliquid inlet, the liquid inflow passage, the negative electrode blockliquid inlet, the liquid inflow passage, and the liquid cooling blockliquid inlet are sequentially communicative with one another; thepositive electrode block liquid outlet, the liquid outflow passage, thenegative electrode block liquid outlet, the liquid outflow passage, andthe liquid cooling block liquid outlet are sequentially communicativewith one another; the lower bottom plate is correspondingly providedwith a lower bottom plate liquid inlet and a lower bottom plate liquidoutlet, and side plates are provided at both sides of the lower bottomplate; the positive electrode block, the multi-bar serially connectedmodule set and the negative electrode block are arranged between the twoside plates on the lower bottom plate after having been sequentiallystacked and mounted, the upper pressing block is disposed at an upperside of the negative electrode block and is fixedly connected with thetwo side plates of the lower bottom plate, and an upper side face of theupper pressing block is fixedly connected with the liquid cooling block;a conduction hole is provided in the liquid cooling block, the liquidcooling block liquid inlet and the liquid cooling block liquid outletare communicative at one end with each other via the conduction hole,and another end thereof is respectively connected with the liquid inletand the liquid outlet of the upper pressing block; the lower bottomplate, the positive electrode block, the multi-bar serially connectedmodule set, the negative electrode block and the upper pressing blockare connected together in the form of a stacked array via a boltcentrally passing therethrough.
 13. The stacked array type liquid-cooledsemiconductor laser according to claim 12, wherein an H-shaped rearplate is fixedly connected at a side of the two side plates of the lowerbottom plate, which is farer away from a light emitting surface.